Rush, which is used as a raw material of tatami (straw mat) in Japan, is a perennial plant classified in the genus Juncus and also known as a herbal medicine called as Toshinso (Juncus decipiens). Rush has no toxicity and is said to have efficacy as a medical plant for an antimicrobial drug, a diuretic drug, an anti-inflammatory drug, a tranquilizer drug and a drug for insomnia. In addition, it is found that rush has an antimicrobial activity against food poisoning bacteria and putrefactive bacteria. Further, rush has an antimicrobial activity against putrefactive bacteria: Bacillus subtilis and Micrococcus sp. as well as food poisoning bacteria: Salmonella sp. Staphylococcus aureus and enterohemorrhagic Escherichia coli O157, O26 and O111. And on the lab-scale, rush with a concentration of around 1 to 10% exerts these antimicrobial activities (for example, see Patent Document 1).
Besides, as a method for producing an enzyme which utilizes a plant as a substrate, proposed is a production method of an enzyme using rush in that rush which has been at least washed with water is powdered, and this rush powder is sterilized and used as a culture substrate to culture filamentous fungi (for example, see Patent Document 2).
According to Patent Document 1, it is revealed that a growth inhibitory effect against mold can be obtained by heating rush in an alkaline solution with pH of 9 or more. This treatment enables rush to be used as a rush material added with a growth inhibitory effect against mold for, for example, building materials and other materials relating to housing; papers; clothing materials; packaging materials relating to food; and the like. In addition, it is also possible to use rush as it is after the alkaline treatment without being washed with water for the purpose of growth inhibition of mold. In this case, it is disclosed that a growth control effect against mold by pH can also be added in addition to a growth inhibitory effect against mold that rush has, which further enhances a growth inhibitory effect of rush against mold.
According to Patent Document 2, rush is used as a substrate when producing a useful enzyme by culturing filamentous fungi. Since rush has a porous and sponge-like inner structure, the inside of rush contains a large amount of air, which is a suitable environment for aerobic microorganisms. Specifically, cut and dried rush is washed with water to remove attached substances, and the rush is further dried and then milled into powder. A required amount of pure water and pectin is added to the rush powder, and the mixture is sterilized by heating and then cooled to room temperature, thereby obtaining a culture substrate. This substrate serves as a medium having a bread-like structure containing moisture. A microorganism to be cultured, for example, filamentous fungi (liquid) which is mold is inoculated to the medium and cultured for several days while maintaining a predetermined temperature. In this case, the microorganism is cultured, for example, over 7 to 30 days or more depending on the kind of the microorganism cultured.